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Westbrook, 23, made second-team All-NBA in his third pro season a year ago, and with the deal cemented his status as an Oklahoma City cornerstone alongside scoring champ Kevin Durant. Oklahoma City lost to the Dallas Mavericks in last season's Western Conference finals and, at 12-3, have the second-best record in the league behind the Chicago Bulls.

The deal, as noted by SI's Chris Mannix, is not a "supermax" deal; Westbrook could've been eligible for an annual salary worth 30 percent of the salary cap. Instead, he opted for a standard max deal that pays him 25 percent of the cap, which enables Oklahoma City to continue locking down key players like James Harden and Serge Ibaka.

Durant in 2010 signed a five-year "supermax" extension with the Thunder that took effect this season and will total about $89 million. That figure was determined before the season by CBA's so-called "Derrick Rose Rule." In order to qualify, the player must have met specific requirements during his four-year rookie contract; an Most Valuable Player award, two All-NBA (first, second or third) team nods, or two All-Star Game starts.

Durant met those guidelines and reaped the benefits—the same maximum salary as a player with seven years in the league. Westbrook, assuming he matches his production from last season, likely would've been able to do the same, but opted not to do so.

Harden and Ibaka are eligible for early extensions as of July 1 though those contracts wouldn't kick in until the 2013-14 season. If Oklahoma City can't reach deals with the players by the October 2012 deadline, they would become restricted free agents in July 2013.

Players in Westbrook's draft class, including Timberwolves power forward Kevin Love, have until Jan. 26 to sign contract extensions; if they don't, they'll become restricted free agents after the 2011-12 season.

Love, according to multiple reports, has been offered a maximum salary but only a four-year deal by the Timberwolves. He took to Twitter to congratulate Westbrook: "Overwhelmed with joy for my brother @russwest44. Put in so much work to be where he is today. You deserve it."

Westbrook was criticized heavily in the postseason over the perception that he was taking too many shots, and it led to speculation over both his relationship with Durant and place in Oklahoma City's plans; one widely circulated rumor had him headed to Boston for Rajon Rondo.

All the while, Westbrook and Durant maintained that there are no problems between them—and Westbrook's extension would serve as supporting evidence, particularly considering his decision not to take 30 percent.